Otolith shape is species specific and is an ideal marker of fish population affiliation. In this study, otolith shape of spottedtail goby Synechogobius ommaturus is used to identify stocks in different spawning locati...Otolith shape is species specific and is an ideal marker of fish population affiliation. In this study, otolith shape of spottedtail goby Synechogobius ommaturus is used to identify stocks in different spawning locations in the Yellow Sea. The main objectives of this study are to explore the potential existence of local stocks of spottedtail goby in the Yellow Sea by analysis of otolith shape, and to investigate ambient impacts on otolith shape. Spottedtail goby was sampled in five locations in the Yellow Sea in 2007 and 2008. Otoliths are described using variables correlated to size (otolith area, perimeter, length, width, and weight) and shape (rectangularity, circularity, and 20 Fourier harmonics). Only standardized otolith variables are used so that the effect of otolith size on the shape variables could be eliminated. There is no significant difference among variables of sex, year, and side (left and right). However, the otolith shapes of the spring stocks and the autumn stocks differ significantly. Otolith shape differences are greater among locations than between years. Correct classification rate of spottedtail goby with the otolith shape at different sampling locations range from 29.7%–77.4%.展开更多
Otolith shape is species-specific in fish.In this study,161 samples of Trumpeter sillago Sillago maculata and 164 of Silver sillago Sillago sihama were collected from Beibu Gulf in July 2009.The main objective of this...Otolith shape is species-specific in fish.In this study,161 samples of Trumpeter sillago Sillago maculata and 164 of Silver sillago Sillago sihama were collected from Beibu Gulf in July 2009.The main objective of this study was to use morphological variables and Fourier harmonics to describe otolith characteristics and use discriminant analyses to separate the two species.Otoliths were measured by traditional one and two dimensional measures(otolith length,width,diameters,area,perimeter,rectangularity and circularity),as well as by Fourier analysis to capture the finer regions of the otolith.Analysis of covariance(ANCOVA) showed that there was significant correlation between morphological variables(diameter,perimeter,otolith length,otolith width,otolith area,density,harmonics 3,harmonics 4,harmonics 5,harmonics 13,harmonics 15,and harmonics 16) and body length.To minimize size effects on the morphological variables between species,only fish with a body length between 90 and 140 mm were included in the data analysis and the variables which had significant relation with body length were transformed using the residual.The result showed that the accuracy of discriminant analysis was 97.8% and 100% for Trumpeter sillago and Silver sillago,respectively.This high accuracy indicated that otolith shape was described accurately by morphological variables and Fourier harmonics,and discriminant analysis was an effective way to identify and separate the two species.展开更多
Removal of the length ef fect in otolith shape analysis for stock identification using length scaling is an important issue; however, few studies have attempted to investigate the ef fectiveness or weakness of this me...Removal of the length ef fect in otolith shape analysis for stock identification using length scaling is an important issue; however, few studies have attempted to investigate the ef fectiveness or weakness of this methodology in application. The aim of this study was to evaluate whether commonly used size scaling methods and normalized elliptic Fourier descriptors(NEFDs) could ef fectively remove the size ef fect of fish in stock discrimination. To achieve this goal, length groups from two known geographical stocks of yellow croaker, L arimichthys polyactis, along the Chinese coast(five groups from the Changjiang River estuary of the East China Sea and three groups from the Bohai Sea) were subjected to otolith shape analysis. The results indicated that the variation of otolith shape caused by intra-stock fish length might exceed that due to inter-stock geographical separation, even when otolith shape variables are standardized with length scaling methods. This variation could easily result in misleading stock discrimination through otolith shape analysis. Therefore, conclusions about fish stock structure should be carefully drawn from otolith shape analysis because the observed discrimination may primarily be due to length ef fects, rather than dif ferences among stocks. The application of multiple methods, such as otoliths shape analysis combined with elemental fingering, tagging or genetic analysis, is recommended for sock identification.展开更多
The Pacific saury Cololabis saira is a commercially important pelagic species with wide distribution in the North Pacific Ocean. Previous studies identified two geographical groups by comparing the radius of otolith a...The Pacific saury Cololabis saira is a commercially important pelagic species with wide distribution in the North Pacific Ocean. Previous studies identified two geographical groups by comparing the radius of otolith annual rings(ROA) of the fish collected during the pre-fishing season. Moreover, understanding the group composition in the mixed catch from the fishing ground is essential for sustainable exploitation of this species. Using samples collected during the fishing season(July–November) from 2016 to 2018, the potential of applying otolith shape analysis as a tool to identify these two mixed groups was tested in this research. Two otolith morphotypes that belong to the eastern group and western group were identified by K-means cluster analysis using Fourier coefficients and ROA. The high classification success of random forest further confirmed the effectiveness of otolith shape analysis. The western group accounted for the majority of catch in July and August at 160?E. With the passing of sampling time and fishing fleets moving westward, the proportion of eastern group gradually increased and finally reached more than 60% of the whole catch in November at 150°E. This result suggests that the eastern and western groups are well mixed during spawning migration. In addition, the temporal and spatial dynamics of their catch composition provide information for their migration route. This study is helpful for improving fisheries management and understanding the short-term stock fluctuation of Pacific saury.展开更多
The geographical variations in life history characteristics of small yellow croaker Larimichthys polyactis, caused by experienced different environmental conditions, have been observed in China seas. Previous studies ...The geographical variations in life history characteristics of small yellow croaker Larimichthys polyactis, caused by experienced different environmental conditions, have been observed in China seas. Previous studies based on spatial distribution, migration route, and body morphometrics suggested a complex stock structure. In this study, to clarify the source of a spawning stock, we investigated the reproduction strategy and inter-structure of the Haizhou Bay (HZB) spawning stock in the middle Yellow Sea from both egg survey and adult otolith increment analysis. Egg and adult samples were collected from three surveys during spawning season in 2013. Distinct spatial and temporal variations were detected in egg distribution and size, and otolith shape analysis of adult fishes revealed two morphotypes with different increment growth using random forest cluster. The results indicate the existence of two components within the same spawning stock in HZB from different wintering grounds, and accordingly special protection should be required for this stock given the significance to maintain connectivity between adjacent subpopulations.展开更多
The Chaenocephalus aceratus were sampled in summers between 1979 and 1990. Their otoliths show pattern of daily microincrements as otoliths of similar species--Pseudochaenichthys georgianus and fishes both temperate a...The Chaenocephalus aceratus were sampled in summers between 1979 and 1990. Their otoliths show pattern of daily microincrements as otoliths of similar species--Pseudochaenichthys georgianus and fishes both temperate and tropical waters. Changes of the microincrements growth pattern and otolith shape are described in relation to larval, hatching and metamorphosis stages have similar patterns for Ps. georgianus and Charnpsocephalus gunnari, reflecting similar habitats in their early life. Width of larvae-postlarvae daily increments are： （1.0-1.6）×10-3 SSI, （1.8-2.8）×10-3 SG1 and （1.5-2.4）×10-3 ANI. They were search and chosen automatically from density profiles of otolith tissues. Tissues were prepared by new saving time and materials way--one time up to 40 ones per microscopic glass. Age of fish estimated from microincrements was alike to that inferred from the body length distribution, otoliths mass （age （years） = 140.82 OM （g） ＋ 0.8546） and otolith shape changes--large in length and surface on medial plane. Those parameters create age groups of close neighbours. They have different environments. C. aceratus due to its adaptation to cold water, attain rapidly large body according to a growth equation： Lt= 75.1 ×10-3 （1-e-0.26（t-0.51）. Among large fishes there were only females.展开更多
The Ps. georgianus （Pseudochaenichthys georgianus） were sampled in the summer between 1979 and 2009 at South Georgia Island, and at South Shetland Island. The otoliths ofPs. georgianus contained microincrements simi...The Ps. georgianus （Pseudochaenichthys georgianus） were sampled in the summer between 1979 and 2009 at South Georgia Island, and at South Shetland Island. The otoliths ofPs. georgianus contained microincrements similar to daily increments in the otoliths of fishes from temperate and tropical waters. The estimated age from microincrements was similar to that inferred from the body length distribution and otoliths mass： age （years） = 81.98 × Otolith Mass （g） - 0.483. Ps. georgianus like all Channichthyidae due to their adoption to cold water, attain rapidly large body in accordance with the parameters of the von Bertalanffy growth equation： L∞ （asymptotic length） = 66.1 cm; K （constant related to coefficient of catabolism） = 0.28; to （age of the fish at initial length） = 0.008 year; L0 （length of the fish at initial age） = 0.15 cm. That fast growth rate （despite the difference in hatching periods between regions at South Georgia Island, and at South Shetland Island） were not changed, confirming, that it is established to cold water by natural selection. Changes of the microincrements growth pattern are described that appear to be related to larval, hatching and metamorphosis, and have similar pattern to those ones previewed in C. aceratus （Chaenocephalus aceratus） and C. gunnarii （Champsocephalus gunnarii）. Larvaes and postlarvaes of that species have similar habitats during early life history, which is reflected in similar otoliths morphology. Width of their daily increments is： 0.0018-0.0028 mm for Ps. georgianus, 0.0015-0.0024 mm for C. gunnarii and 0.001-0.0016 mm for C. aceratus. The age and developments periods of South Georgia＇s icefish （common name and the abbreviation = SGI for Ps. georgianus as this species was found only there in the past） estimated from otolith was validated by their different geographical distribution depending on the currents and the presence of their food-krill in them. Postlarvae and early juvenile stages were concentrated at the south-western side of the island shelves deeper than 200 m, where currents are weaker in comparison to surface and where juvenes and small krill prevail. Older and mature fish, over 3 or 4 years old, were numerous on the north-eastern side of the islands shelves in regions of strong vortices that concentrate krill to high densities. As life in the currents needs greater ability to swimming as a large, mature and 4 years old fish had increased their ability to swim up to 4 times growing and developing from inshore larvae. During that, their otoliths become more flattened （up to 3 times） and elongated for better fulfil its functions in the higher swimming speed. However, similar species C. aceratus and C. gunnari have more flattened and elongated otoliths than Ps. georgianus and have larger geographical occurrence from Palmer Archipelago to Kerguelen. The least elongated means the highest otolith, which reflects the highest body of Ps. georgianus, which help this species to stay on the shelf during swimming. High body gives less drifting during swimming in the currents. Evolution of otolith shape is linked with a body shape to decrease resistance and achieve high speed of swimming. During development, Ps. georgianus use different currents and countercurrents to catch different krill stages. System of current is natural environment of life ofPs. georgianus.展开更多
Otolith morphology is widely used for fish stock identification. The sulcus, a structure on the medial side of the otolith, is an important feature in morphological analysis. This study was conducted to evaluate the f...Otolith morphology is widely used for fish stock identification. The sulcus, a structure on the medial side of the otolith, is an important feature in morphological analysis. This study was conducted to evaluate the feasibility of using sulcus morphology for stock identification and to compare its performance with commonly used otolith morphology analysis. Otoliths were collected and analyzed from three geographical groups (the Huanghe (Yellow) River estuary, HHE;the Jiaozhou Bay, JZB;and the Changjiang (Yangtze) River estuary, CJE) of yellow drum Nibea albiflora. The results show that the analysis of sulcus morphology based on shape indices (SIs), elliptic Fourier coefficients (EFc), and a combination of the two parameters identified stocks at overall classification rates of 51.0%, 72.5%, and 73.2%, respectively. These classification rates are similar to those obtained using otolith morphology analysis (57.0%, 73.8%, and 76.5% by SIs, EFc, and their combination, respectively). The findings suggest that sulcus morphology is comparable to the commonly used otolith morphology for identifying stocks of sciaenids, such as the yellow drum. For both otolith and sulcus morphology, EFc could identify the stocks more efficiently than SIs, while the combination of SIs and EFc was even better.展开更多
基金Supported by the National Basic Research Program of China (973 program) (No.2005CB422306)the National Natural Science Foundation of China under the Science Fund for Creative Research Groups (No.40821004)the Natural Science Foundation of Shandong Province (No.Y2008D21)
文摘Otolith shape is species specific and is an ideal marker of fish population affiliation. In this study, otolith shape of spottedtail goby Synechogobius ommaturus is used to identify stocks in different spawning locations in the Yellow Sea. The main objectives of this study are to explore the potential existence of local stocks of spottedtail goby in the Yellow Sea by analysis of otolith shape, and to investigate ambient impacts on otolith shape. Spottedtail goby was sampled in five locations in the Yellow Sea in 2007 and 2008. Otoliths are described using variables correlated to size (otolith area, perimeter, length, width, and weight) and shape (rectangularity, circularity, and 20 Fourier harmonics). Only standardized otolith variables are used so that the effect of otolith size on the shape variables could be eliminated. There is no significant difference among variables of sex, year, and side (left and right). However, the otolith shapes of the spring stocks and the autumn stocks differ significantly. Otolith shape differences are greater among locations than between years. Correct classification rate of spottedtail goby with the otolith shape at different sampling locations range from 29.7%–77.4%.
基金supported by the Natural Science Foundation of Shandong Province (Y2008D21)the National Basic Research Program of China (973 Program, No.2005CB422306)
文摘Otolith shape is species-specific in fish.In this study,161 samples of Trumpeter sillago Sillago maculata and 164 of Silver sillago Sillago sihama were collected from Beibu Gulf in July 2009.The main objective of this study was to use morphological variables and Fourier harmonics to describe otolith characteristics and use discriminant analyses to separate the two species.Otoliths were measured by traditional one and two dimensional measures(otolith length,width,diameters,area,perimeter,rectangularity and circularity),as well as by Fourier analysis to capture the finer regions of the otolith.Analysis of covariance(ANCOVA) showed that there was significant correlation between morphological variables(diameter,perimeter,otolith length,otolith width,otolith area,density,harmonics 3,harmonics 4,harmonics 5,harmonics 13,harmonics 15,and harmonics 16) and body length.To minimize size effects on the morphological variables between species,only fish with a body length between 90 and 140 mm were included in the data analysis and the variables which had significant relation with body length were transformed using the residual.The result showed that the accuracy of discriminant analysis was 97.8% and 100% for Trumpeter sillago and Silver sillago,respectively.This high accuracy indicated that otolith shape was described accurately by morphological variables and Fourier harmonics,and discriminant analysis was an effective way to identify and separate the two species.
基金Supported by the National Basic Research Program of China(973 Program)(No.2015CB453302)the NSFC-Shandong Joint Fund for Marine Science Research Centre(No.U1606404)the Aoshan Science and Technology Innovation Project(No.2015ASKJ02-04)
文摘Removal of the length ef fect in otolith shape analysis for stock identification using length scaling is an important issue; however, few studies have attempted to investigate the ef fectiveness or weakness of this methodology in application. The aim of this study was to evaluate whether commonly used size scaling methods and normalized elliptic Fourier descriptors(NEFDs) could ef fectively remove the size ef fect of fish in stock discrimination. To achieve this goal, length groups from two known geographical stocks of yellow croaker, L arimichthys polyactis, along the Chinese coast(five groups from the Changjiang River estuary of the East China Sea and three groups from the Bohai Sea) were subjected to otolith shape analysis. The results indicated that the variation of otolith shape caused by intra-stock fish length might exceed that due to inter-stock geographical separation, even when otolith shape variables are standardized with length scaling methods. This variation could easily result in misleading stock discrimination through otolith shape analysis. Therefore, conclusions about fish stock structure should be carefully drawn from otolith shape analysis because the observed discrimination may primarily be due to length ef fects, rather than dif ferences among stocks. The application of multiple methods, such as otoliths shape analysis combined with elemental fingering, tagging or genetic analysis, is recommended for sock identification.
基金supported by the National Natural Science Foundation of China (No. 41930534)the Fundamental Research Funds for the Central Universities to Ocean University of China (Nos. 201762015 and 201822027)。
文摘The Pacific saury Cololabis saira is a commercially important pelagic species with wide distribution in the North Pacific Ocean. Previous studies identified two geographical groups by comparing the radius of otolith annual rings(ROA) of the fish collected during the pre-fishing season. Moreover, understanding the group composition in the mixed catch from the fishing ground is essential for sustainable exploitation of this species. Using samples collected during the fishing season(July–November) from 2016 to 2018, the potential of applying otolith shape analysis as a tool to identify these two mixed groups was tested in this research. Two otolith morphotypes that belong to the eastern group and western group were identified by K-means cluster analysis using Fourier coefficients and ROA. The high classification success of random forest further confirmed the effectiveness of otolith shape analysis. The western group accounted for the majority of catch in July and August at 160?E. With the passing of sampling time and fishing fleets moving westward, the proportion of eastern group gradually increased and finally reached more than 60% of the whole catch in November at 150°E. This result suggests that the eastern and western groups are well mixed during spawning migration. In addition, the temporal and spatial dynamics of their catch composition provide information for their migration route. This study is helpful for improving fisheries management and understanding the short-term stock fluctuation of Pacific saury.
基金Supported by the Fundamental Research Funds for the Central Universities(No.201562030)
文摘The geographical variations in life history characteristics of small yellow croaker Larimichthys polyactis, caused by experienced different environmental conditions, have been observed in China seas. Previous studies based on spatial distribution, migration route, and body morphometrics suggested a complex stock structure. In this study, to clarify the source of a spawning stock, we investigated the reproduction strategy and inter-structure of the Haizhou Bay (HZB) spawning stock in the middle Yellow Sea from both egg survey and adult otolith increment analysis. Egg and adult samples were collected from three surveys during spawning season in 2013. Distinct spatial and temporal variations were detected in egg distribution and size, and otolith shape analysis of adult fishes revealed two morphotypes with different increment growth using random forest cluster. The results indicate the existence of two components within the same spawning stock in HZB from different wintering grounds, and accordingly special protection should be required for this stock given the significance to maintain connectivity between adjacent subpopulations.
文摘The Chaenocephalus aceratus were sampled in summers between 1979 and 1990. Their otoliths show pattern of daily microincrements as otoliths of similar species--Pseudochaenichthys georgianus and fishes both temperate and tropical waters. Changes of the microincrements growth pattern and otolith shape are described in relation to larval, hatching and metamorphosis stages have similar patterns for Ps. georgianus and Charnpsocephalus gunnari, reflecting similar habitats in their early life. Width of larvae-postlarvae daily increments are： （1.0-1.6）×10-3 SSI, （1.8-2.8）×10-3 SG1 and （1.5-2.4）×10-3 ANI. They were search and chosen automatically from density profiles of otolith tissues. Tissues were prepared by new saving time and materials way--one time up to 40 ones per microscopic glass. Age of fish estimated from microincrements was alike to that inferred from the body length distribution, otoliths mass （age （years） = 140.82 OM （g） ＋ 0.8546） and otolith shape changes--large in length and surface on medial plane. Those parameters create age groups of close neighbours. They have different environments. C. aceratus due to its adaptation to cold water, attain rapidly large body according to a growth equation： Lt= 75.1 ×10-3 （1-e-0.26（t-0.51）. Among large fishes there were only females.
文摘The Ps. georgianus （Pseudochaenichthys georgianus） were sampled in the summer between 1979 and 2009 at South Georgia Island, and at South Shetland Island. The otoliths ofPs. georgianus contained microincrements similar to daily increments in the otoliths of fishes from temperate and tropical waters. The estimated age from microincrements was similar to that inferred from the body length distribution and otoliths mass： age （years） = 81.98 × Otolith Mass （g） - 0.483. Ps. georgianus like all Channichthyidae due to their adoption to cold water, attain rapidly large body in accordance with the parameters of the von Bertalanffy growth equation： L∞ （asymptotic length） = 66.1 cm; K （constant related to coefficient of catabolism） = 0.28; to （age of the fish at initial length） = 0.008 year; L0 （length of the fish at initial age） = 0.15 cm. That fast growth rate （despite the difference in hatching periods between regions at South Georgia Island, and at South Shetland Island） were not changed, confirming, that it is established to cold water by natural selection. Changes of the microincrements growth pattern are described that appear to be related to larval, hatching and metamorphosis, and have similar pattern to those ones previewed in C. aceratus （Chaenocephalus aceratus） and C. gunnarii （Champsocephalus gunnarii）. Larvaes and postlarvaes of that species have similar habitats during early life history, which is reflected in similar otoliths morphology. Width of their daily increments is： 0.0018-0.0028 mm for Ps. georgianus, 0.0015-0.0024 mm for C. gunnarii and 0.001-0.0016 mm for C. aceratus. The age and developments periods of South Georgia＇s icefish （common name and the abbreviation = SGI for Ps. georgianus as this species was found only there in the past） estimated from otolith was validated by their different geographical distribution depending on the currents and the presence of their food-krill in them. Postlarvae and early juvenile stages were concentrated at the south-western side of the island shelves deeper than 200 m, where currents are weaker in comparison to surface and where juvenes and small krill prevail. Older and mature fish, over 3 or 4 years old, were numerous on the north-eastern side of the islands shelves in regions of strong vortices that concentrate krill to high densities. As life in the currents needs greater ability to swimming as a large, mature and 4 years old fish had increased their ability to swim up to 4 times growing and developing from inshore larvae. During that, their otoliths become more flattened （up to 3 times） and elongated for better fulfil its functions in the higher swimming speed. However, similar species C. aceratus and C. gunnari have more flattened and elongated otoliths than Ps. georgianus and have larger geographical occurrence from Palmer Archipelago to Kerguelen. The least elongated means the highest otolith, which reflects the highest body of Ps. georgianus, which help this species to stay on the shelf during swimming. High body gives less drifting during swimming in the currents. Evolution of otolith shape is linked with a body shape to decrease resistance and achieve high speed of swimming. During development, Ps. georgianus use different currents and countercurrents to catch different krill stages. System of current is natural environment of life ofPs. georgianus.
基金Supported by the National Key Basic Research Program of China(973Program)(No.2015CB453302)the NSFC-Shandong Joint Fund for Marine Science Research Centre(No.U1606404)
文摘Otolith morphology is widely used for fish stock identification. The sulcus, a structure on the medial side of the otolith, is an important feature in morphological analysis. This study was conducted to evaluate the feasibility of using sulcus morphology for stock identification and to compare its performance with commonly used otolith morphology analysis. Otoliths were collected and analyzed from three geographical groups (the Huanghe (Yellow) River estuary, HHE;the Jiaozhou Bay, JZB;and the Changjiang (Yangtze) River estuary, CJE) of yellow drum Nibea albiflora. The results show that the analysis of sulcus morphology based on shape indices (SIs), elliptic Fourier coefficients (EFc), and a combination of the two parameters identified stocks at overall classification rates of 51.0%, 72.5%, and 73.2%, respectively. These classification rates are similar to those obtained using otolith morphology analysis (57.0%, 73.8%, and 76.5% by SIs, EFc, and their combination, respectively). The findings suggest that sulcus morphology is comparable to the commonly used otolith morphology for identifying stocks of sciaenids, such as the yellow drum. For both otolith and sulcus morphology, EFc could identify the stocks more efficiently than SIs, while the combination of SIs and EFc was even better.
